More from WebMD

Dec. 6, 2011 -- For a while, it seemed the bedbug had gone the way of the Edsel automobile and cold water flats. Not anymore -- as we’ve learned. They’re back with a vengeance, and experts now seem to know why.

Bedbugs may not get as much play in the media as they did in the summer of 2010, but they are here to stay, experts warned at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in Philadelphia. New research presented here helps explain why they are back and a lot of it has to do with an ability to outsmart existing treatments.

We saw hide nor hair from these vermin in the U.S. for close to 60 years, but now the number of bedbug infestations in homes, hotel rooms, and the like has jumped 10- to 100-fold since 1990.

What Is a Bed Bug?

Bedbugs are wingless, rust-colored insects. They are about the size of an apple seed. They don’t spread disease, but they do bite and munch on your blood. Their bites can trigger allergic reactions, including welts and itching in some people. Other people may not have any symptoms after a bite.

Part of the reason they are here en masse is their tremendous capacity for inbreeding. Researchers studied bed bugs from buildings in North Carolina and New Jersey and found an uncanny family resemblance among them. This was confirmed in another study of 21 bedbug infestations from Maine to Florida.

Others species don’t survive after inbreeding, but bed bugs don’t just survive, they thrive, says Coby Schal, PhD. He is an entomologist at the North Carolina State University in Raleigh, N.C. “A single mated female can create a whole new population or infestation,” he says.

"We are just seeing the tip of the iceberg," Schal says. "They are here to stay for awhile.”

But this doesn’t necessarily mean you should avoid movie theaters, hotel rooms, or other places where bedbugs lurk.

“Bedbugs don’t hitchhike on people,” he says. “They are more likely to take a blood meal for five to 10 minutes and leave.”

This means they piggyback on your stuff instead. “You can pick up bed bugs on furniture and clothing,” he says.

Beat BedBugs at Their Own Game

“Movie theaters are dark, so bedbugs are difficult to spot,” Schal says. Don’t skip the blockbuster. Instead, strip down when you arrive home and place all of your clothes in the dryer at high heat for 30 minutes.

“When kids come back from college for Christmas break, take preventive measures if their dorm has been infested,” he says. Put all their belongings in the dryer on high heat or leave them outside in the cold air to chill, as the cold will kill them off too,” he says.

When Schal checks into a hotel room, the first thing he does is take out his flashlight and check the bed, mattress seams, headboard, coffee table, and dresser. “I look in cracks and crevices to see if there is any sign of bedbugs,” he says.

Here’s another tip: “Remove the headboard if it is not too heavy and look behind it,” he says. “Bedbugs don’t like to be disturbed by housekeeping when they make the bed or change the sheets.” That is why they may congregate behind or under headboards, where they are less likely to be disturbed.

Viviana Temino, MD, says that bedbug bites can look a lot like hives and that she is seeing a lot more of them these days. She is an assistant professor of allergy and immunology at the University of Miami’s Miller School of Medicine.

“We have to start to think of bedbugs as possible diagnosis of hives, especially if hives happen at night and in the day you are OK,” she says. Temino was not at the meeting, but reviewed the findings for WebMD.

So, what do you do if you find any bedbugs or bedbug bites?

That is the tricky part, as we are running out of solutions, says Ken Haynes, PhD. He is an entomologist at the University of Kentucky in Louisville. Insecticide resistance is present in 88% of bedbug populations in different parts of the country, he says.

Resistance means that many of the treatments don’t work anymore. Haynes and colleagues are now trying to understand what went wrong and seeing if they can fix it.

Unless and until they get some answers, “we need to have a better scheme for managing insecticide resistance,” he says. Using heat treatment instead of chemicals may play a role.